Original Article
Effects of regular exercise on obesity and type 2 diabete mellitus in Korean children: improvements glycemic control and serum adipokines level
J. Phys. Ther. Sci. 27: 1903–1907, 2015
Sung Soo Lee1), Sunghwun K ang2)* 1) Department
of Coaching, College of Sports Science, Dong-A University, Republic of Korea of Exercise Physiology, Department of Physical Education, Korea Air Force Academy: 335-2 Danjae-ro, Namil-myeon, Sangdang-gu, Cheongju-si, Chungcheongbuk-do 363-849, Republic of Korea
2) Laboratory
Abstract. [Purpose] The aim of the study was to clarify the effects of regular exercise on lipid profiles and serum adipokines in Korean children. [Subjects and Methods] Subjects were divided into controls (n=10), children who were obese (n=10), and children with type 2 diabetes mellitus (n=10). Maximal oxygen uptake (VO2max), body composition, lipid profiles, glucagon, insulin and adipokines (leptin, resistin, visfatin and retinol binding protein 4) were measured before to and after a 12-week exercise program. [Results] Body weight, body mass index, and percentage body fat were significantly higher in the obese and diabetes groups compared with the control group. Total cholesterol, triglycerides, low-density lipoprotein cholesterol and glycemic control levels were significantly decreased after the exercise program in the obese and diabetes groups, while high-density lipoprotein cholesterol levels were significantly increased. Adipokines were higher in the obese and diabetes groups compared with the control group prior to the exercise program, and were significantly lower following completion. [Conclusion] These results suggest that regular exercise has positive effects on obesity and type 2 diabetes mellitus in Korean children by improving glycemic control and reducing body weight, thereby lowering cardiovascular risk factors and adipokine levels. Key words: Leptin, Resistin, Visfatin (This article was submitted Jan. 29, 2015, and was accepted Mar. 7, 2015)
INTRODUCTION Historically, type 2 diabetes mellitus (T2DM) has been considered an adult disease. However, recent epidemiological studies have reported an increase incidence of T2DM in children and adolescents in a number of countries1, 2). Data from the 2007 US National Diabetes Fact Sheet indicate that 7.8% of the population and 0.22% of those aged ≤ 20 years have diabetes1). T2DM has, also been associated with the growing pre valence of childhood obesity2). In addition, increases in childhood obesity have been accompanied by an increased incidence of type 2 diabetes in youth3, 4). In Asia the prevalence of T2DM has increased raidly in recent decades and is characterized by a younger age and lower body mass index (BMI) at onset compared with Western countries5). Early treatment of T2DM in children is essential to slow or delay disease progression and prevent complications.
*Corresponding author. Sunghwun Kang (E-mail:
[email protected]) ©2015 The Society of Physical Therapy Science. Published by IPEC Inc. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives (by-ncnd) License .
Lifestyle modifications (e.g., dietary adaptations) are required, and many pediatric patients also require glucose lowering medication to achieve satisfactory glycemic control6). Increased physical activity must be also considered as part of treatment: based on mounting evidence of the benefits of regular exercise on abdominal obesity in adults7). There is also evidence in children suggesting that engaging in regulatory exercise is associated with a lower waist circumference and reduced visceral fat6). Leptin, visfatin, resistin and retinol binding protein 4 (RBP4) are important adipokines that are involved in inflammation, insulin resistance, obesity and cardiovascular disease8–12). They may also have a role in the pathogenesis of metabolic syndrome relating to obesity and insulin resistance13). Despite this evidence, diet control and regular exercise are still lacking in children. This study was designed to examine the effects of a regular exercise program on serum adipokine levels and glycemic control in children who were obese or who had T2DM. SUBJECTS AND METHODS The 1998 Children and Adolescent Physical Growth Standard proposed by The Korean Society of Pediatrics was used in the assessments of subjects. Ten overweight
1904 J. Phys. Ther. Sci. Vol. 27, No. 6, 2015 Table 1. Descriptive characteristics of the study participants Variable Height (cm) Weight (kg) BMI (kg/m 2) %fat (%) VO2max (mL/min/kg)
CO
OB
T2DM
pre
post
pre
post
pre
post
162.00±1.06 55.74±2.33 21.18±0.72 16.77±2.19 33.17±1.41
162.35±1.08 55.80±2.19 21.13±0.70 16.85±2.17 33.98±1.04
166.35±1.93 73.52a ±2.66 26.56a ±0.58 30.54a ±1.11 28.05a ±1.12
167.28±2.10 69.16ab±2.64 24.65ab±0.62 26.96ab±0.87 31.16ab±1.36
161.60±2.25 63.98a ±4.43 24.28a ±1.27 28.97a ±1.90 30.12a ±1.61
161.65±2.23 62.93a ±4.19 23.88ab±1.20 27.94ab±1.69 33.57b±1.31
Values are mean ± SE; ap 120% were assigned to the obese group (OB, mean±standard error age, 16.7±0.19 years), ten children with normal weight were assigned to the healthy control group (CO, 15.0±0.01 years), and ten children were assigned to the T2DM group (16.8±0.22 years; metformin therapy: n=6, repaglinide therapy: n=2) The thildren in the T2DM group were D University Hospital inpatients with a 2-h glucose tolerance test ≤ 140 mg/dL, blood sugar level ≥ 200 mg/dL and no other complicating diseases. The participants and their caregivers submitted written informed consent prior to enrolment. The study recruited via poster advertisements and the internet and was approved by the D University Hospital Institutional Review Board after medical examination and diagnosis by medical specialists. Aerobic exercise (modified from Roberts et al. 6)) was conducted for 40–60 minutes per session four times a week, for 12 weeks. Participants achieved 50% of their oxygen consumption through the VO2max test. In weeks 1–4, participants engaged in 30–40 minutes of aerobic exercise walking/running) at a school field under the supervision of a professional trainer. Participants were monitored using a Polar System (Polar Electro, Kempele, Finland) that calculated heart rate reserve (HRR). In weeks 5–12, participants exercised in a similar manner but for 40–50 minutes at a HRR equivalent to 60% of VO2max. Each session was preceded and followed by a 5-minute warm-up and cool-down6). Body composition testing was performed by measuring height, weight, body fat and BMI with the use of a Venus 5.5 impedance analyzer (Jawon Medical, Seoul, Korea). An exercise loading test was performed using an Inter track 6025 treadmill (Taeha, Seoul, Korea) and a Quark b2 gas analyzer (Cosmed, Rome, Italy) using the lowest grade for physical activity for children in the modified Balke treadmill protocols. Criteria for determining maximal exercise included: i) the intensity of exercise was increased when the oxygen intake was < 2.0 mL/kg/min, ii) heart rate was not increasing, iii) Borg rating of perceived exertion was > 17, iv) category ratio scale (CR10) was > 7, and v) respiratory exchange rate was > 1.1514). All blood samples were collected at our laboratory at 08:00 following a 12-hour overnight fast. After a 10-minute rest in a comfortable chair, fasting blood was collected from the median cubital vein into a plain tube. Each blood sample was centrifuged at 3,000 g for 10 minutes at 4 °C and stored at −70 °C until required for analysis.
Lipid profiles (TC, TG, HDL-c and LDL-c) were quantified using commercial, enzyme-based kits (Asan, City, Korea). Plasma (2 uL) and the enzyme solution (300 uL) were rotated and incubated in a water bath at 37 °C for 5 minutes for color development. Optical density was determined using a UVmini-1240 spectrophotometer (Shimadzu, Tokyo, Japan) with the blank as a control. Glycemic control in the fasting state was determined by the homeostasis model assessment (HOMA-IR): [fasting glucose (mg/dL) × fasting insulin (μU/mL)] / 405 All serum samples were submitted for a solid phase sandwich enzyme-linked immunosorbant assay (ELISA) measurement of RBP4 (Sino Biological company location) using the standard curve method with a dilution series of a provided human RBP4. Leptin, resistin, visfatin, insulin and glucagon were measured using a Bio-plex 200 human serum adipokine (panel B) LINCOplex kit (BioRad, Hercules, CA) with an accuracy of 93%, inter-assay variation (% CV) of
